Practice- To exercise oneself by repeated performance in order to acquire a skill.
Living- Having life; being alive; not dead. Some Christ believers never leave the practice field because of; fear, complacency, denial, misinformation, and many other reasons. You can practice being a Christ believer your entire life unfortunately, that will never give you eternal life.
To be a living Christ believer one must move pass the practice field and get in the game full time. While in the game you are still practicing and learning but being in the game means there is a prize at the end and it is eternal